title: Ghrelin, sleep reduction and evening preference: relationships to CLOCK 3111 T/C SNP and weight loss.
abstract: BACKGROUND
  Circadian Locomotor Output Cycles Kaput (CLOCK), an essential element of the positive regulatory arm in the human biological clock, is involved in metabolic regulation. The aim was to investigate the behavioral (sleep duration, eating patterns and chronobiological characteristics) and hormonal (plasma ghrelin and leptin concentrations) factors which could explain the previously reported association between the CLOCK 3111T/C SNP and weight loss.
  
  
  RESULTS
  We recruited 1495 overweight/obese subjects (BMI: 25-40 kg/m(2)) of 20-65 y. who attended outpatient obesity clinics in Murcia, in southeastern Spain. We detected an association between the CLOCK 3111T/C SNP and weight loss, which was particularly evident after 12-14 weeks of treatment (P = 0.038). Specifically, carriers of the minor C allele were more resistant to weight loss than TT individuals (Mean±SEM) (8.71±0.59 kg vs 10.4±0.57 kg) C and TT respectively. In addition, our data show that minor C allele carriers had: 1. shorter sleep duration Mean ± SEM (7.0±0.05 vs 7.3±0.05) C and TT respectively (P = 0.039), 2. higher plasma ghrelin concentrations Mean ± SEM (pg/ml) (1108±49 vs 976±47)(P = 0.034); 3. delayed breakfast time; 4. evening preference and 5. less compliance with a Mediterranean Diet pattern, as compared with TT homozygotes.
  
  
  CONCLUSIONS
  Sleep reduction, changes in ghrelin values, alterations of eating behaviors and evening preference that characterized CLOCK 3111C carriers could be affecting weight loss. Our results support the hypothesis that the influence of the CLOCK gene may extend to a broad range of variables linked with human behaviors.
authors.affiliation: Department of Physiology, Faculty of Biology, University of Murcia, Murcia, Spain. garaulet@um.es
authors.forename: Marta
authors.initials: M
authors.lastname: Garaulet
authors.forename: Carmen
authors.initials: C
authors.lastname: Sánchez-Moreno
authors.forename: Caren E
authors.initials: CE
authors.lastname: Smith
authors.forename: Yu-Chi
authors.initials: YC
authors.lastname: Lee
authors.forename: Francisco
authors.initials: F
authors.lastname: Nicolás
authors.forename: Jose M
authors.initials: JM
authors.lastname: Ordovás
mesh_terms: D000328:Adult; D000368:Aged; D056926:CLOCK Proteins / Q000235:genetics*; D005247:Feeding Behavior / Q000502:physiology; D005260:Female; D054439:Ghrelin / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000150:complications / Q000235:genetics; D050177:Overweight / Q000097:blood / Q000150:complications / Q000235:genetics; D020641:Polymorphism, Single Nucleotide / Q000502:physiology; D012890:Sleep / Q000235:genetics / Q000502:physiology; D012893:Sleep Wake Disorders / Q000097:blood / Q000150:complications / Q000235:genetics*; D011795:Surveys and Questionnaires; D015431:Weight Loss / Q000235:genetics* / Q000502:physiology; D055815:Young Adult
chemical_list: D054439:Ghrelin; D056926:CLOCK Proteins; C538943:CLOCK protein, human